THE TRANSMISSIBLE GASTROENTERITIS CORONAVIRUS CONTAINS A SPHERICAL CORE-SHELL CONSISTING OF M-PROTEIN AND N-PROTEIN

Coronaviruses are enveloped RNA viruses involved in a variety of patho logies that affect animals and humans. Existing structural models of t hese viruses propose a helical nucleocapsid under the virion envelope as the unique internal structure. In the present work, we have analyze d the Structure of the transmissible gastroenteritis coronavirus. The definition of its organization supports a new structural model for cor onaviruses, since a spherical, probably icosahedral, internal core has been characterized. Disruption of these cores induces the release of N-protein-containing helical nucleocapsids. Immunogold mapping and pro tein analysis of purified cores showed that they consist of M and N pr oteins, M being the main core shell component. This surprising finding , together with the fact that M protein molecules are also located in the virion envelope, indicates that a reconsideration of the assembly and maturation of coronaviruses, as well as a study of potential M-pro tein subclasses, is needed.